Staging: otus: off by one in usbdrvwext_siwessid()

A 33 char ESSID is too long and it could cause a buffer overflow
a couple lines below when we put a NULL terminator on the end.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>